[Python-checkins] bpo-46502: Remove "How do I tell incomplete input" from FAQ (GH-30925)
pablogsal
webhook-mailer at python.org
Wed Jan 26 18:49:14 EST 2022
https://github.com/python/cpython/commit/f0a648152f2d8011f47cc49873438ebaf01d3f82
commit: f0a648152f2d8011f47cc49873438ebaf01d3f82
branch: main
author: Mateusz Łoskot <mateusz at loskot.net>
committer: pablogsal <Pablogsal at gmail.com>
date: 2022-01-26T23:49:06Z
summary:
bpo-46502: Remove "How do I tell incomplete input" from FAQ (GH-30925)
Since,
- Py_CompileString no longer allows to distinguish "incomplete input"
from "invalid input"
- there is no alternative solution available from the Python C API
due to how the new parser works (rewritten in 3.9)
- the only supported way is to manually import the codeop module from C
and use its API as IDLE does, and accept its own complications
it is desirable to remove this Q&A from the official FAQ.
files:
M Doc/faq/extending.rst
diff --git a/Doc/faq/extending.rst b/Doc/faq/extending.rst
index fd32b097335e5..1d2aca6f4c8d9 100644
--- a/Doc/faq/extending.rst
+++ b/Doc/faq/extending.rst
@@ -254,7 +254,6 @@ For Red Hat, install the python-devel RPM to get the necessary files.
For Debian, run ``apt-get install python-dev``.
-
How do I tell "incomplete input" from "invalid input"?
------------------------------------------------------
@@ -273,127 +272,6 @@ you. You can also set the :c:func:`PyOS_ReadlineFunctionPointer` to point at you
custom input function. See ``Modules/readline.c`` and ``Parser/myreadline.c``
for more hints.
-However sometimes you have to run the embedded Python interpreter in the same
-thread as your rest application and you can't allow the
-:c:func:`PyRun_InteractiveLoop` to stop while waiting for user input.
-A solution is trying to compile the received string with
-:c:func:`Py_CompileString`. If it compiles without errors, try to execute the
-returned code object by calling :c:func:`PyEval_EvalCode`. Otherwise save the
-input for later. If the compilation fails, find out if it's an error or just
-more input is required - by extracting the message string from the exception
-tuple and comparing it to the string "unexpected EOF while parsing". Here is a
-complete example using the GNU readline library (you may want to ignore
-**SIGINT** while calling readline())::
-
- #include <stdio.h>
- #include <readline.h>
-
- #define PY_SSIZE_T_CLEAN
- #include <Python.h>
-
- int main (int argc, char* argv[])
- {
- int i, j, done = 0; /* lengths of line, code */
- char ps1[] = ">>> ";
- char ps2[] = "... ";
- char *prompt = ps1;
- char *msg, *line, *code = NULL;
- PyObject *src, *glb, *loc;
- PyObject *exc, *val, *trb, *obj, *dum;
-
- Py_Initialize ();
- loc = PyDict_New ();
- glb = PyDict_New ();
- PyDict_SetItemString (glb, "__builtins__", PyEval_GetBuiltins ());
-
- while (!done)
- {
- line = readline (prompt);
-
- if (NULL == line) /* Ctrl-D pressed */
- {
- done = 1;
- }
- else
- {
- i = strlen (line);
-
- if (i > 0)
- add_history (line); /* save non-empty lines */
-
- if (NULL == code) /* nothing in code yet */
- j = 0;
- else
- j = strlen (code);
-
- code = realloc (code, i + j + 2);
- if (NULL == code) /* out of memory */
- exit (1);
-
- if (0 == j) /* code was empty, so */
- code[0] = '\0'; /* keep strncat happy */
-
- strncat (code, line, i); /* append line to code */
- code[i + j] = '\n'; /* append '\n' to code */
- code[i + j + 1] = '\0';
-
- src = Py_CompileString (code, "<stdin>", Py_single_input);
-
- if (NULL != src) /* compiled just fine - */
- {
- if (ps1 == prompt || /* ">>> " or */
- '\n' == code[i + j - 1]) /* "... " and double '\n' */
- { /* so execute it */
- dum = PyEval_EvalCode (src, glb, loc);
- Py_XDECREF (dum);
- Py_XDECREF (src);
- free (code);
- code = NULL;
- if (PyErr_Occurred ())
- PyErr_Print ();
- prompt = ps1;
- }
- } /* syntax error or E_EOF? */
- else if (PyErr_ExceptionMatches (PyExc_SyntaxError))
- {
- PyErr_Fetch (&exc, &val, &trb); /* clears exception! */
-
- if (PyArg_ParseTuple (val, "sO", &msg, &obj) &&
- !strcmp (msg, "unexpected EOF while parsing")) /* E_EOF */
- {
- Py_XDECREF (exc);
- Py_XDECREF (val);
- Py_XDECREF (trb);
- prompt = ps2;
- }
- else /* some other syntax error */
- {
- PyErr_Restore (exc, val, trb);
- PyErr_Print ();
- free (code);
- code = NULL;
- prompt = ps1;
- }
- }
- else /* some non-syntax error */
- {
- PyErr_Print ();
- free (code);
- code = NULL;
- prompt = ps1;
- }
-
- free (line);
- }
- }
-
- Py_XDECREF(glb);
- Py_XDECREF(loc);
- Py_Finalize();
- exit(0);
- }
-
-
How do I find undefined g++ symbols __builtin_new or __pure_virtual?
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